A. Field of the Invention
This invention relates to the field of medical instruments and their user interfaces, and more particularly to a user interface and control method for a medical instrument such as a dialysis machine.
B. Description of Related Art
Dialysis machine are used for treating patients with inadequate kidney function. Hemodialysis machines typically include, among other things, an extracorporeal blood circuit comprising an arterial line, a blood pump, a dialyzer having a semipermeable membrane and a venous line. Blood is removed from the patient and pumped by the blood pump through the arterial line to the blood compartment of the dialyzer, where toxins and excess water are removed from the patient's blood. A dialysate solution is circulated on the other side of the membrane and carries away the toxins and removed water. The blood is then returned to the patient via the venous line. Peritoneal dialysis machines prepare a dialysate solution which is introduced into the patient's peritoneal cavity.
Dialysis machines typically have some sort of controls to regulate the operation of the machine. Such controls in the past were a rather unattractive and hard to use set of dials and switches that required trained medical professionals to use properly. More contemporary machines have a single user interface to allow a patient or medical practitioner to interact with the machine and adjust machine operation or treatment parameters, e.g., blood pump rate, dialysate temperature or flow rate, treatment time, heparin pump rate, etc.
The patent to Grogan et al., U.S. Pat. No. 5,326,476, which is incorporated by reference herein, describes a touch screen that is used to control the operation of a hemodialysis machine. The touch screen is connected to a host microprocessor which controls operation of most of the active components of the machine. When the user wishes to change a treatment parameter, the user touches an icon on the touch screen and a key pad with an enter key pops up on the screen. The user enters the new value by touching the numbers on the key pad and pressing the enter button on the key pad. A verify button is then pressed on the touch screen if the user wishes to confirm the change. The patent also briefly describes a method of touching the touch screen to program a time-varying parameter, such as ultrafiltration removal over the course of a dialysis session.
User interfaces that solely depend on a touch screen as a means for entering and confirming parametric values, such as described in the Grogan et al. patent, are vulnerable to failures in the touch screen display. If the touch screen is defective, the computer system may not receive the correct information from the touch screen or interpret the information incorrectly. The present invention was designed to provide for redundancy and safety verification of parametric value changes independent of the operation of the touch screen, and thereby avoid accidental or unintended changes of parameters in the event of a defect in the touch screen.
The user interface of the present invention provides for the combination of a touch screen, and at least one hard key that are separate and apart from the touch screen, whereby both the touch screen and the hard keys have to be pressed to enter and verify a change in a parametric value pertinent to the treatment or the operation of the machine. The computer control system for the machine also uses host and safety backup microprocessors which are responsive to the touch screen and hard keys to perform internal verification and confirmation checking procedures to verify that the change in parametric value requested by the user is proper. These features combine to offer safety benefits, robustness, and ease of use that are believed to be superior to user interfaces known in the prior art.
Another object of the invention is to provide a user interface design for a medical instrument that is especially easy to use by a person that is not a technically trained medical professional, i.e., by the patient or a member of the patient's family.